1. Field of the Invention
This invention relates to apparatus for the processing of webs of photographic materials and the like and more particularly to an improved turnaround for handling the web in a processing tank and for reversal of the direction of the web in the midportion of the processing.
2. Description of the Prior Art
It has heretofore been proposed to direct an elongated strip or web of photographic material through a tank for processing. The apparatus heretofore employed included, in sequence, pairs of introducing rollers at the top of the tank, downwardly directing pairs of rollers with a turnaround at the bottom of the tank, and upwardly directing pairs of rollers with pairs of delivery rollers at the top of the tank on the opposite side from the introducing rollers. The turnaround structure heretofore employed included nip rolls between which the web was gripped, for advancing the web and interposed guide plates for directing the web from one set of nip rolls to the next.
The use of nip rolls for propulsion of the web within the processing fluid as well as the use of guide plates for directing the web, had a tendency to scratch the web and did not provide the best exposure of the web to the processing fluid with agitation of the fluid and soft or delicate webs would collapse upon contact with the guide plates. The prior apparatus also had high power requirements due to the internal friction of the driving mechanism for the web. Nip rolls are also troublesome in use because of the difficulty in maintaining constant pressure on the web to drive the web to avoid slipping because of insufficient pressure and to avoid pinching and bruising because of excessive pressure.